An ion mobility separator (or ion mobility device) which separates and detects ions by ion mobility is widely used as an on-site measurement device for environmental analysis, explosive detection, illegal drug detection, chemical agent detection, and the like due to the characteristic that it can operate even under atmospheric pressure without requiring a vacuum pump. The ion mobility separator separates ions in a gas phase under atmospheric pressure by utilizing the fact that the movement speed of the ions in the gas phase is different depending on the three-dimensional structure of a molecular ion. Therefore, a separation method is greatly different from a mass spectrometer which separates molecular ions in vacuum electric field or magnetic field. As a result, it is expected to separate isomeric ions having the same mass-to-charge ratio (m/z) difficult to separate with a mass spectrometer using an ion mobility separator. As one of the methods which is frequently used in recent years for an ion mobility separator, there is provided a Field asymmetric ion mobility spectrometer (FAIMS) or a Differential ion mobility spectrometer (DMS).
A mass spectrometer (MS) has high selectivity because ions can be separated by mass-to-charge ratio (m/z) of molecular ion in vacuum and it is possible to separate and detect ions with high sensitivity and high accuracy. A mass spectrometer is commonly used as a detector of liquid chromatograph (LC) and gas chromatograph (GC) and analytical methods called liquid chromatography mass spectrometry (LC/MS) and gas chromatography mass spectrometry (GC/MS) are often used. High sensitivity and high resolution are realized by time-separating samples, impurities, and other samples by LC and GC.
In addition, in a mass spectrometer, tandem mass spectrometry is used which decomposes measurement-target ions and measures decomposed ions (fragment ions) to enable separation from other impurity ions. This results in high mass resolution. Furthermore, the technology of a mass spectrometer capable of high sensitivity measurement such as a mass spectrometer realizing high resolution such as a Time-of-flight mass spectrometer (TOF/MS), a Fourier-transform mass spectrometer (FT/MS), a Fourier-transform ion cyclotron resonance mass spectrometer (FTICR/MS), and an Orbitrap mass spectrometer, or a Triple quadrupole mass spectrometer, and a Quadrupole mass spectrometer is advanced and the mass spectrometer is widely spreading mainly in bio and medical fields.
As described above, an ion mobility separator has different separation performance from a mass analyzer, and thus a measurement method combining a mass analyzer and an ion mobility separator has also been reported. PTLs 1 and 2 disclose examples of an apparatus in which an ion source, a FAIMS, and a mass spectrometer are combined. The FAIMS is located in a succeeding stage of the ion source and located in a preceding stage of the mass spectrometer. PTL 3 discloses an example of a mass spectrometer. Ion flow paths are bent in the succeeding stage of the ion source and in the preceding stage of the MS.